-=NOTE: These pages are automatically updated once perday from the Asterisk subversion repository when the repository changes revisions. Anychanges made to this page will be automatically overwritten with thelatest version from http://svn.digium.com/view/asterisk/branches/.

Overview
-------
Asterisk currently supports configurable RTP packetization per codec for
select RTP-based channels.
Channels
-------
These channel drivers allow RTP packetization on a user/peer/friend
or global level:
chan_sip
chan_skinny
chan_h323
chan_ooh323 (Asterisk-Addons)
chan_gtalk
chan_jingle
Configuration
-------
To set a desired packetization interval on a specific codec,
append that inteval to the allow= statement.
Example:
allow=ulaw:30,alaw,g729:60
No packetization is specified in the case of alaw in this example,
so the default of 20ms is used.
Autoframing
-------
In addition, chan_sip has the ability to negotiate the desired
framing at call establishment.
In sip.conf if autoframing=yes is set in the global section, then
all calls will try to set the packetization based on the remote
endpoint's preferences. This behaviour depends on the endpoints
ability to present the desired packetization (ptime:) in the SDP.
If the endpoint does not include a ptime attribute, the call will
be established with 20ms packetization.
Autoframing can be set at the global level or on a user/peer/friend
basis. If it is enabled at the global level, it applies to all
users/peers/friends regardless of their prefered codec packetization.
Codec framing options
-------
The following table lists the minimum and maximum values that are
valid per codec, as well as the increment value used for each.
Please note that the maximum values here are only recommended
maximums, and should not exceed the RTP MTU.
Name Min Max Default Increment
g723 30 300 30 30
gsm 20 300 20 20
ulaw 10 150 20 10
alaw 10 150 20 10
g726 10 300 20 10
ADPCM 10 300 20 10
SLIN 10 70 20 10
lpc10 20 20 20 20
g729 10 230 20 10
speex 10 60 20 10
ilbc 30 30 30 30
g726_aal2 10 300 20 10
Invalid framing options are handled based on the following rules:
1. If the specified framing is less than the codec's minimum, then
the minimum value is used.
2. If the specific framing is greater than the codec's maximum, then
the maximum value is used
3. If the specificed framing does not meet the increment requirement,
the specified framing is rounded down to the closest valid
framing options.
example allow=ulaw:33 will set the codec to 30ms framing
4. If no framing is specified in the allow= directive, then the
codec default is used.

-=NOTE: These pages are automatically updated once perday from the Asterisk subversion repository when the repository changes revisions. Anychanges made to this page will be automatically overwritten with thelatest version from http://svn.digium.com/view/asterisk/branches/.

Overview
-------
Asterisk currently supports configurable RTP packetization per codec for
select RTP-based channels.
Channels
-------
These channel drivers allow RTP packetization on a user/peer/friend
or global level:
chan_sip
chan_skinny
chan_h323
chan_ooh323 (Asterisk-Addons)
chan_gtalk
chan_jingle
Configuration
-------
To set a desired packetization interval on a specific codec,
append that inteval to the allow= statement.
Example:
allow=ulaw:30,alaw,g729:60
No packetization is specified in the case of alaw in this example,
so the default of 20ms is used.
Autoframing
-------
In addition, chan_sip has the ability to negotiate the desired
framing at call establishment.
In sip.conf if autoframing=yes is set in the global section, then
all calls will try to set the packetization based on the remote
endpoint's preferences. This behaviour depends on the endpoints
ability to present the desired packetization (ptime:) in the SDP.
If the endpoint does not include a ptime attribute, the call will
be established with 20ms packetization.
Autoframing can be set at the global level or on a user/peer/friend
basis. If it is enabled at the global level, it applies to all
users/peers/friends regardless of their prefered codec packetization.
Codec framing options
-------
The following table lists the minimum and maximum values that are
valid per codec, as well as the increment value used for each.
Please note that the maximum values here are only recommended
maximums, and should not exceed the RTP MTU.
Name Min Max Default Increment
g723 30 300 30 30
gsm 20 300 20 20
ulaw 10 150 20 10
alaw 10 150 20 10
g726 10 300 20 10
ADPCM 10 300 20 10
SLIN 10 70 20 10
lpc10 20 20 20 20
g729 10 230 20 10
speex 10 60 20 10
ilbc 30 30 30 30
g726_aal2 10 300 20 10
Invalid framing options are handled based on the following rules:
1. If the specified framing is less than the codec's minimum, then
the minimum value is used.
2. If the specific framing is greater than the codec's maximum, then
the maximum value is used
3. If the specificed framing does not meet the increment requirement,
the specified framing is rounded down to the closest valid
framing options.
example allow=ulaw:33 will set the codec to 30ms framing
4. If no framing is specified in the allow= directive, then the
codec default is used.